The present invention relates generally to waveform production apparatus and methods for producing waveforms of musical tones, voices or other desired sounds by connecting and synthesizing waveforms read out from a waveform memory or the like. More particularly, the present invention relates to an improved waveform production apparatus and method, which, by preparing in advance not only normal style-of rendition (hereinafter referred to as “rendition style”) modules, such as attack-, release-, body- and joint-related rendition style modules, to be used for generating normal sounds but also shot-tone-related rendition style modules to be used for producing special sounds that heretofore could not be reproduced faithfully, can more faithfully express or reproduce color (timbre) variations effected by various rendition styles or various articulation peculiar to natural musical instruments. Note that the present invention is applicable extensively to all fields of equipment, apparatus or methods capable of producing waveforms of musical tones, voices or other desired sounds, such as automatic performance apparatus, computers, electronic game apparatus or other types of multimedia equipment, not to mention ordinary electronic musical instruments. It should also be appreciated that, in this specification, the term “tone” is used to embrace a voice or other sound than a musical tone and similarly the terms “tone waveform” are used to embrace a waveform of a voice or any other desired sound, rather than to refer to a waveform of a musical tone alone.
The so-called “waveform memory readout” technique has been well known in the art, in accordance with which waveform data (i.e., waveform sample data), encoded by a desired encoding scheme, such as the PCM (Pulse Code Modulation), DPCM (Differential PCM) or ADPCM (Adaptive Differential PCM), are prestored in a waveform memory of an electronic musical instrument so that a tone waveform can be produced by reading out an appropriately-selected set of waveform data from the waveform memory at a rate corresponding to a desired tone pitch. There have been known various types of waveform memory readout techniques. Most of the known waveform memory readout techniques are intended to produce a waveform from the beginning to end of each tone to be generated. Among various examples of the known waveform memory readout techniques is one that prestores waveform data of an entire waveform from the beginning to end of a tone to be generated, and one that prestores waveform data of a full waveform for an attack portion or the like of a tone having complicated variations but prestores a predetermined loop waveform segment for a sustain or other portion having little variations. In this specification, the terms “loop waveform” are used to refer to a waveform to be read out in a repeated (looped) fashion.
In the waveform memory readout techniques prestoring waveform data of an entire waveform from the beginning to end of a tone to be generated or waveform data of a full waveform for an attack portion or the like of a tone, there must be prestored a multiplicity of different sets of waveform data corresponding to a variety of rendition styles (or articulation) and thus a great storage capacity is required for storing the multiplicity of sets of waveform data.
Further, although the above-mentioned technique designed to prestore waveform data of an entire waveform can faithfully express tone color (timbre) variations effected by various rendition styles (or articulation) peculiar to a natural musical instrument, it can only reproduce tones just in the same manner as represented by the prestored data, and thus it tends to encounter poor controllability and editability. For example, it has been very difficult for the technique to perform control of waveform characteristics, such as performance-data-based time axis control, of the waveform date corresponding to a desired rendition style or kind of articulation.
To address the above-discussed inconveniences of the conventional techniques, a more sophisticated technique for facilitating realistic reproduction and control of various rendition styles (articulation) peculiar to natural musical instruments has been proposed in Japanese Patent Laid-open Publication No. 2000-122665 and the like; this more sophisticated techniques is commonly known as a “SAEM” (Sound Articulation Element Modeling) technique. According to the SAEM technique, attack-, release-, body- and joint-related rendition style modules are prepared in advance so that a continuous tone waveform can be produced by time-serially combining two or more of the prepared rendition style modules. For example, the SAEM technique can produce a waveform of a tone by applying an attack-related rendition style module to a rise portion (i.e., attack portion) of the tone, a body-related rendition style module to a steady portion of the tone and a release-related rendition style module to a fall portion (i.e., release portion) of the tone and then connecting together waveform data corresponding to these rendition style modules. Note that the joint-related rendition style module is a module to be used to interconnect adjoining tones (or adjoining tone portions) via a desired rendition style.
The conventionally-known SAEM technique can significantly increase variations of rendition styles by variously combining the attack-, release-, body- and joint-related rendition style modules. However, in the case of a characteristic tone, such as a tone having a very short time length or duration (i.e., one-shot waveform) like a staccato performance tone, or a tone ending in glissando immediately after its rise, rendition styles (articulation) of the attack and release portions are closely related to each other, namely, closely influence each other. Because such a characteristic tone integrally includes its attack and release portions and has a very short duration, it will hereinafter be referred to also as a “shot tone”. For the reason stated above, it has been very difficult to faithfully reproduce such a characteristic tone by just combining the attack-and release-related rendition style modules to produce a connected waveform. In the first place, for a tone of a very short time length (shot tone), such as a staccato performance tone, which has a very short time interval from the articulation of the attack portion to the articulation of the release portion, it is hardly possible to separately prepare in advance respective rendition style modules for the attack and release portions. Even where the respective rendition style modules for the attack and release portions can be separately prepared in advance through some extra effort, such rendition style modules often can not be appropriately used in combination with other kinds of rendition style modules, such as body-related rendition style module, of a normal tone than the shot tone, and therefore it would be meaningless or worthless to bother to prepare such separate rendition style modules for the attack and release portions through extra effort.
Namely, with the conventionally-known SAEM technique, it has been extremely difficult to faithfully reproduce, as a realistic tone, a characteristic shot tone having attack and release portions closely related to, or closely influencing, each other, such as one of a very short time length like a staccato performance tone, or one ending in glissando immediately after its rise.